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Mpega
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1995-06-23
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117 lines
-------------------------------------------------------------------------------
mpega 1.0 (23-Jun-1995) (68020+)
-------------------------------------------------------------------------------
Distribution Conditions
-----------------------
This program is copyright (c) 1995 by Stephane TAVENARD.
It may be distributed freely under the condition that no profit is
gained from its distribution, nor from any other program distributed
in the same package.
Permission is granted to distribute this package by Bulletin Board
systems or network sites, under the condition that no fee is charged
on downloading it.
All files that are part of this package have to be distributed
together and none of them may be changed in any way other than
archiving or crunching. The only exception to this rule are the
icons, including the tooltypes, which may be changed to accommodate
them to the rest of the disk it is distributed on.
This program is distibuted as freeware.
Disclamer
---------
This package is provided "as is" without warranty of any kind.
The author assumes no responsibility or liability whatsoever
for any damage or dataloss caused by using this package.
Introduction
------------
What is MPEG audio ?
It's a very efficient audio compression standard. Actually, there is 3
compression methods, named layer I, II & III. Layer III is more efficient
than layer II, witch is more efficient than layer I. But, more efficient
means more complex. For this reasons, Layer III is not implemented yet.
MPEG audio allows to compress a 16-bits PCM sound file from 1.2 to
32 times.
Why is it so hard to make a real time MPEG audio decoder ?
MPEG audio decoding requires a lot of arithmetic calculation, so a lot of CPU
power is required. Normally, MPEG audio decoding is made with help of a DSP.
History
-------
V1.0 23-Jun-1995 First aminet release
Description
-----------
You need at least a 68020 CPU to use it !
This is an highly optimized MPEG audio decoder. This one can decode MPEG audio
standard streams, layer I & II. The output can be either a raw PCM file, an AIFF
file or AMIGA-built in audio device. The output samples can be 16 or 8 bits wide
(for audio 16 bits are reduced to 14 bits, due to hardware limitations).
Some results:
on my A1200/GVPTurboI 68030/40MHz/4Mo Fast RAM,
SCSI Hard drives with Squirrel interface:
Bitstream parameters field is <layer>/<bitrate>/<sfreq>/<mode>
<bitrate> is in kbits/sec
<sfreq> is in kHz
<mode> are M:mono (=single channel), S:stereo, J:joint-stereo, D:dual-channel
Options are the options that follows the mpega command
Decoding output was always a ram file.
Name | Parameters | Duration | Options | CPU Time used
--------------------------+------------+----------+---------+--------------
FRIENDLY.MP2 | 2/032/44/M | 10.24 s | -d1 -q2 | 16.38 s
FRIENDLY.MP2 | 2/032/44/M | 10.24 s | -d1 -q1 | 11.46 s
FRIENDLY.MP2 | 2/032/44/M | 10.24 s | -d1 -q0 | 8.94 s
FRIENDLY.MP2 | 2/032/44/M | 10.24 s | -d2 -q2 | 8.50 s
FRIENDLY.MP2 | 2/032/44/M | 10.24 s | -d2 -q1 | 6.04 s
FRIENDLY.MP2 | 2/032/44/M | 10.24 s | -d2 -q0 | 4.82 s
FRIENDLY.MP2 | 2/032/44/M | 10.24 s | -d4 -q2 | 4.78 s
FRIENDLY.MP2 | 2/032/44/M | 10.24 s | -d4 -q1 | 3.56 s
FRIENDLY.MP2 | 2/032/44/M | 10.24 s | -d4 -q0 | 2.94 s
DEMO_AUD.MP2 | 2/112/44/S | 32.29 s | -d4 -q1 | 25.36 s
THINGS.MP1 | 1/128/44/S | 10.03 s | -d4 -q1 | 9.82 s
IBYT_78S.MP2 | 2/224/44/S | 20.38 s | -d4 -q1 | 18.36 s
THINGS.MP2 | 2/128/44/J | 23.30 s | -d4 -q1 | 18.34 s
ex32.mp2 | 2/032/44/M | 15.86 s | -d2 -q1 | 9.38 s
excerpt-Love_Supreme.mp2 | 2/096/44/M | 15.86 s | -d2 -q1 | 11.62 s
GREETING.MP2 | 2/064/44/M | 6.79 s | -d2 -q1 | 4.56 s
TEST.MP2 | 2/064/44/M | 15.18 s | -d2 -q1 | 9.94 s
ex384.mp2 | 2/384/44/M | 7.86 s | -d2 -q1 | 7.30 s
2001.mp2 | 2/080/32/S | 93.24 s | -d4 -q1 | 51.76 s
dune32.mp2 | 2/032/32/M | 66.53 s | -d2 -q1 | 30.98 s
shimmering.mp2 | 2/056/32/M | 43.27 s | -d2 -q1 | 22.76 s
Thanks to my friend, AMIGA, the best computer ever made.
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Stéphane TAVENARD (ANGERS/France)